A putative < i > de novo < /i > evolved gene required for spermatid chromatin condensation in < i > Drosophila melanogaster < /i >

by Emily L. Rivard, Andrew G. Ludwig, Prajal H. Patel, Anna Grandchamp, Sarah E. Arnold, Alina Berger, Emilie M. Scott, Brendan J. Kelly, Grace C. Mascha, Erich Bornberg-Bauer, Geoffrey D. Findlay Comparative genomics has enabled the identification of genes that potentially evolvedde novo from non-coding sequences. Many such genes are expressed in male reproductive tissues, but their functions remain poorly understood. To address this, we conducted a functional genetic screen of over 40 putativede novo genes with testis-enriched expression inDrosophila melanogaster and identified one gene,atlas, required for male fertility. Detailed genetic and cytological analyses showed thatatlas is required for proper chromatin condensation during the final stages of spermatogenesis. Atlas protein is expressed in spermatid nuclei and facilitates the transition from histone- to protamine-based chromatin packaging. Complementary evolutionary analyses revealed the complex evolutionary history ofatlas. The protein-coding portion of the gene likely arose at the base of theDrosophila genus on the X chromosome but was unlikely to be essential, as it was then lost in several independent lineages. Within the last ~15 million years, however, the gene moved to an autosome, where it fused with a conserved non-coding RNA and evolved a non-redundant role in male fertility. Altogether, this study provides insight into the integration of novel genes into biological processes, the links between genomic in...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research